106 MISSOURI BOTANICAL GARDEN". 



sperm ends its pavement phase of development (Stage II, 

 f. 7) ; b, that between this time, and the final closure of the 

 endosperm cavity (Stage III, f. 14) ; and c, the period 

 following until maturation (Stage IV) . It will be convenient 

 for cross reference to speak of these stages and periods. 

 Period I occupies about eight weeks. The young seed is then 



mm. loner bv 2 mm 



meas 



7.5 by 7 mm. (broad). Period II occupies about three 



to four weeks. The fruit is 9.5 mm. broad by 10 mm. long; 

 the seed 7 mm. long by 2.5-3 mm. broad. It is relatively 

 a very short period and one of rapid change, characterized 

 by the development of the endosperm, and marked topo- 

 graphic changes in the ovule in general. The third period 

 occupies a period, following the closure of the endosperm 

 cavity, covering about 15 weeks, and is characterized by the 

 development of the embryo, which, until the end of period 

 II, remains very small. 



Stage I. Beginning of the First Period. 



The pistil (f. A), with the exception of the stigma, is en- 

 closed in the involucre. Three pistils 

 of which persists normally. 



Carpel The whole pistil at the tim 



are 



meas 



ures about 3 mm. in length by 1.8 mm. broad. The dorsi- 

 ventral diameter (1.2-1.4 mm.) is somewhat less. The 

 locule is small, and completely filled by the anatropous, 

 central basal ovule. The short style is traversed by a canal 

 lined by secretory cells — pollen 



secretory cells — pollen tube guiding tissue. The 

 canal is continuous with a groove, which at the upper part 

 of the ovule is single, but bifurcates as it passes downward, 

 one groove passing on each side of the funicle (f. 2-2e). In 

 front of the micropyle the glandular tissue spreads out to 

 form a cap over the exostome (f. 2). These grooves per- 

 sist and enlarge, and may be traced (f. 11) throughout the 

 whole development of the fruit. 



At this time, with the exception of the epidermis of colum- 

 nar cells, external and internal (endocarp), there is to be 

 recognized only the tanniferous layer of idioplasts. Within 





